ALBERT

Description: SummaryMultifactorial experiments on winter barley cv. Igri grown after potatoes were made from 1981 to 1983 on silty clay loam soils at Rothamsted. All tested combinations of seven factors, each at two levels: with and without autumn pesticide (aldicarb), two sowing dates (September or October), with and without a fungicidal seed treatment (‘Baytan’), with and without spring and summer fungicides, two amounts of nitrogen, two times of applying nitrogen and with and without a growth regulator (‘Terpal’). Growth, development, yield, nitrogen uptake, pests and diseases were monitored. Sowing in September, fungicide sprays in spring and summer, and the growth regulator had the largest mean benefits on grain yield (+0·80, +0·56 and +0·34 t/ha respectively). Some factors interacted with sowing date; thus aldicarb, the fungicide sprays in spring and summer and the later timing of N all increased yield more on the September-than on the October-sown barley. The larger yields on the September-sown plots were associated with more ears/m2 (978 v. 744) and, in spite of fewer grains per ear (17·8 v. 20·1), more grains per m2 (17·6 v. 14·7 × 103), but lighter grains (39·2 v. 42·3 mg). The largest yields each year (ca. 8.0–8.5 t/ha) were obtained from September-sown barley fully protected from pests and from pathogens in spring and summer and given N in April rather than in March.The aphid vectors of barley yellow dwarf virus were sufficiently common and infective in two of the three autumns to infect the September-sown barley sufficiently that their control by aldicar b enhanced yield. Nematodes, slugs and dipterous stem borers were not numerous enough to be damaging in any year. Mildew in autumn was controlled by the seed treatment, but effects on yield were inconsistent. Mildew in spring and summer was more abundant on the October-than on the September-sown barley; it was controlled by fungicide sprays, which increased yield significantly each year. Leaf blotch was more abundant on the September-sown barley.

Description: SUMMARYWinter wheat cv. Avalon was sown in autumn 1981, 1982 and 1983 on a clay loam soil following two cereal crops. Multifactorial experiments tested the effects of combinations of the following eight factors, each at two levels: rotation, sowing date, timing of nitrogen, amount of nitrogen, growth regulator, pesticide, spring fungicide and summer fungicide.The best 16-plot mean grain yields in 1982–4 were respectively 8·7, 10·2 and 11·1 t/ha. Rotation had the largest effect on grain yield. Wheat following barley was severely infected with take-all and yielded, on average over 3 years, 2·2 t/ha less than wheat following oats. Take-all was more severe on wheat sown in mid-September than in mid-October; its effects on yield were lessened by early timing of N in 1982. Take-all decreased growth and N uptake mainly after anthesis, and also number of ears and dry weight per grain. Sowing in mid-September compared with mid-October decreased yield of wheat after barley by an average of 0·8 t/ha because take-all was more severe. Early sowing had negligible effects on grain yield of wheat after oats, but increased straw dry weight by 1·1 t/ha.Spring fungioide increased yield by an average of 0·3 t/ha. Effects were larger after barley than after oats, associated with a greater incidence of eyespot after barley. Summer fungioide increased yield by an average of 0·3 t/ha. Foliar diseases were slight in all 3 years. Fusarium ear blight and sharp eyespot were prevalent in 1982 and were not well controlled by the fungioide treatments. Fungicide temporarily decreased the incidence of some components of the mioroflora on the ears. Pesticide increased grain yield of wheat after oats only in 1984, when aphids on the ears were numerous. Aphids were present on early-sown plots in all three autumns but there was little barley yellow dwarf virus infection even without pesticide. Pesticide always decreased the number of nematodes after harvest to fewer than present before sowing. Populations never approached levels expected to affect yield.Early N application (main application early March) resulted in a larger grain yield in 1982 than N applied a month later. In 1983 and 1984 grain yield and N uptake by the grain were greater with the late application, especially when wheat was sown early. The soil contained more mineral N in the autumn of 1982 and 1983 than in 1981. Straw weight was always greater with early than with late application. Increasing the amount of N applied from 163 to 223 kg/ha increased N uptake by 40 kg/ha and grain yield by 0·5 t/ha after oats and by 0·6 t/ha after barley. N uptake in grain plus straw by the best yielding crops ranged from 205 kg/ha in 1982 to 246 kg/ha in 1984.Chlormequat applied at the start of stem extension shortened the stems at maturity by 2 cm each year. In 1984 it inoreased yield of early-sown wheat by 0·3 t/ha and also decreased lodging, which did not occur in the first 2 years.

Description: SummaryMulti-factorial experiments on winter wheat cv. Hustler in autumn 1979 and 1980 sown on a clay loam soil following potatoes tested the effects of combinations of the following eight factors, each at two levels: sowing date; amount of nitrogen; division of nitrogen; timing of nitrogen; irrigation; autumn pesticide (aldicarb); summer aphicide (pirimicarb); and fungicide (carbendazim, tridemorph, maneb and captafol).The mean grain yields of all plots in 1980 and 1981 were respectively 9·6 and 8·3 t/ha; the best eight-plot means were 11·2 and 9·9 t/ha. Fungicides had the largest effect on grain yield, increasing it by 0·8 and 1·7 t/ha in 1980 and 1981, mainly by increasing grain size. Effects were greater with earlier sowing and the larger amount of nitrogen. Benefits from fungicide were well related to the control of leaf diseases, mainly Septoria spp., which became severe after anthesis. Fungicide temporarily decreased the number of saprophytic fungi on the developing ears. Aphids that appeared in autumn on plots sown in mid-September were controlled by autumn pesticide, which also prevented the spread of barley yellow dwarf virus that occurred only in 1981. Consequently, yield of early-sown plots in 1981 was increased by autumn pesticide, but only when the severe infection with leaf diseases was controlled by fungicide. Autumn pesticide decreased nematode populations. Aphid populations in summer were small and yield was unaffected by the decrease in numbers that followed application of an aphicide.Sowing on 20 or 15 September, as compared with 19 or 30 October, caused faster growth and development and greater uptake of N from the soil early in the season. Effects were smaller after April: earlier sowing increased total dry weight by 2·5–3·0 t/ha and, when leaf diseases and barley yellow dwarf virus were controlled, increased yield by 0·9-l·0t/ha. Increasing the amount of N applied by 70 kg/ha (from 105 or 80), increased yield only in 1980 and then only when fungicide was used. Extra N decreased yield in 1981 in the absence of fungicide. Extra N always increased N uptake and decreased grain size. Applying mostor all of the Non 4 or 19 March instead of 15 or 23 April resulted in less uptake of N from anthesis onwards and smaller yield, especially in 1980. N in three applications instead of one had negligible effect. Trickle irrigation decreased yield slightly, despite delaying leaf senescence and increasing straw weight. Attributes of wheat on best yielding plots differed little between years. Average values were: 534 ears/m2; 40·7 grains/ear; 40·4 mg/grain; 18·8 t/ha total dry matter and 214 kg N/ha uptake by grain plus straw.